Also processes markup in transpile. (#119)

Like how the Svelte compiler works, we should first process the markup,
before we can process the script and style, to make sure we get a
representative result.

Author: MaartenX

packages/language-server/src/plugins/svelte/SvelteDocument.ts

@@ -220,6 +220,8 @@ async function transpile(document: Document, preprocessors: PreprocessorGroup =
     let processedScript: Processed | undefined;
     let processedStyle: Processed | undefined;
 
+    preprocessor.markup = preprocessors.markup;
+
     if (preprocessors.script) {
         preprocessor.script = async (args: any) => {
             const res = await preprocessors.script!(args);